DSL MODEM UTILIZING LOW DENSITY PARITY CHECK CODES

摘要

A DSL modem with a receiver (40) and a transmitter (30) includes an LPDC (54) encoder which utilizes a generation matrix G which is derived from a substantially deterministic H matrix in order to generate redundant parity bits for a block of bits. The H matrix is determined by assigning "ones" of a first Nj randomly or deterministically. Then, beginning with the second column, assignment of "ones" is carried out deterministically with each "1" in a previous ancestor column generating a "1" in the next descendant column based on the rule that a descendant is placed one position below or above an ancestor. As a result, descending or ascending diagonals are generated. When distributing "ones" in any given column, care is taken to ensure that no rectangles are generated in conjunction with other "ones" in the current column and previous columns. By avoiding generation of rectangles, diagonals are interrupted.